Temperature-driven elastocaloric enhancement in liquid crystal elastomers
[Description of methods used for collection/generation of data]: Differential scanning calorimetry measurements were performed using DSC Q1000 (TA Instruments) on both the LCE and its precursor. The sample pan utilized for both measurements was the hermetically sealed Tzero aluminum pan (TA Instrume...
| Autores: | , , , , |
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| Tipo de recurso: | conjunto de datos |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:dnet:digitalcsic_::b45765fdf1b311dd16badfdb129c143d |
| Acceso en línea: | http://hdl.handle.net/10261/429239 https://doi.org/10.20350/digitalCSIC/18308 |
| Access Level: | acceso embargado |
| Palabra clave: | Liquid crystal elastomers Infrared thermography Mesogens Elastocaloric effect Thermo-mechanical performance |
| Sumario: | [Description of methods used for collection/generation of data]: Differential scanning calorimetry measurements were performed using DSC Q1000 (TA Instruments) on both the LCE and its precursor. The sample pan utilized for both measurements was the hermetically sealed Tzero aluminum pan (TA Instruments). The heating rate was consistently maintained at 5 °C/min. The temperature modulation parameters were set to a period of 50 seconds and an amplitude of ± 0.663 °C. Before each heating procedure, a 15-minute isothermal interval was applied to allow the equipment to stabilize and reach the designated modulation parameters. Three heat cycles were programmed per measurement with each heat-cool cycle followed by a Newtonian cooling quench. The initial and secondary heat-cool cycles effectively erased the thermal history of the samples. The values presented herein were gathered from the third and final heating cycle. Broadband Dielectric Spectroscopy (BDS) measurement of the prepared LCE material was taken using the Alpha-Beta Impedance Analyzer (Novocontrol). The measurement frequency range was 10^[-1] to 10^[7] Hz. The sample was positioned between 20-mm diameter gold-plated electrodes and subsequently loaded into the Active Sample Cell (Novocontrol) sample stage. The sample was proportioned with a larger diameter than the electrodes to ensure an overhang and prevent short-circuit. The root mean square of the applied AC voltage was 1.0 Vrms. To investigate the polymer dynamics, dielectric measurements were conducted in isothermal mode with a temperature step value of 5 °C/min from -120 to 100 °C/min. The temperature control of each isothermal measurement was maintained by the Quatro Cryosystem (Novocontrol), exhibiting a temperature stability better than ± 0.28$ K. Dynamic mechanical analysis (DMA) measurements were performed using DMA Q800 (TA Instruments) in tension mode. LCE samples were portioned into 25~mm long strips with a width of 2-6 mm. The single-frequency measurement was conducted at a frequency of 1~Hz. The oscillation amplitude was set to 0.37 strain. The sample was initially equilibrated at -100 °C for 5 minutes and then heated up to 70 °C at a heating rate of 2 °C/min. Tensile equipment: A custom-built tensile setup was developed to perform the deformation cycles required for direct measurements of the eC effect. A belt-drive motor provided strain load with an accuracy of ± 0.1 mm. The loading strain rate was set such that the loading strain was reached within 0.2 s, while unloading was performed at the maximum attainable rate of the motor, corresponding to -1200 mm/s. The sample stage was enclosed within a PID-controlled heating chamber to enable precise temperature regulation. The tensile apparatus was housed inside a polystyrene enclosure for temperature regulation, and active cooling was achieved by introducing a controlled nitrogen gas flow into the enclosure. Temperature measurements: Infrared thermography was employed to conduct contact-less temperature measurements. A FLIR A655sc (Teledyne FLIR) with 25°C field of view is pointed towards the thermal window of the polystyrene case. To minimize IR reflections and background noise, the upper surface of the polystyrene enclosure was uniformly covered with black electrical tape. All IR videos were captured at a frame rate of 50 frames per second. The sample temperature was extracted as the mean value of the central third of the visible LCE surface, both in the undeformed and elongated states. |
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